Prior art switching voltage regulators (such as discontinuous buck voltage regulators) may implement dynamic voltage scaling in order to optimize power consumption by using critical path gate speed as the feedback for switching control. Various techniques have been disclosed for measuring the critical path gate speed, including a ring oscillator that generates an oscillator signal with a frequency proportional to the gate speed of the critical path circuit (where the gate speed is inversely proportional to the propagation delay of the critical path circuit). The error between the oscillator frequency and a reference frequency represents the gate speed error used as feedback for switching control. In a discontinuous buck mode voltage regulator, an inductor charge cycle is triggered when the oscillator frequency falls below the reference frequency. Dynamic voltage scaling may be employed in any suitable application, for example, to optimize power consumption of a microprocessor that is configured to operate at different speeds depending on software dynamics, load dynamics, etc.